Pete

[Pete H]

Good evening all,  I wonder if someone could help please?  I have a MS260 which for some time now has been almost impossible to start.  I’ve cleaned the carb that many times I just mention it and it detaches itself.  I’ve checked fuel and impulse lines which to the naked eye look good as with ignition/spark.  I’ve heard that crank seals can be a problem, but, would this give the above problems?  I do not have the equipment to do vacuum pressure checks.  Or should I just replace the carb??? (And hope)

thanks all,

Pete

 

[openspaceman]

1 hour ago, Pete H said:

Good evening all,  I wonder if someone could help please?  I have a MS260 which for some time now has been almost impossible to start.  I’ve cleaned the carb that many times I just mention it and it detaches itself.  I’ve checked fuel and impulse lines which to the naked eye look good as with ignition/spark.  I’ve heard that crank seals can be a problem, but, would this give the above problems?  I do not have the equipment to do vacuum pressure checks.  Or should I just replace the carb??? (And hope)

thanks all,

Pete

 

Before you start ordering parts take the exhaust off and have a look at the piston and rings. You could take a photo and post it here.

 

Try and get both rings in view and a bit of the skirt.

[Steven P]

Does it run OK when it does start?

If you suspect the fuel supply (cleaning the carb etc) what about the fuel and air filters? A lot cheaper to check than replacing the carb and you'd probably need to do that anyway once it it working OK. After that a carb kit and rebuild it maybe.. but there will be better minds than mine along shortly.

 

 

 

Edit:

Seeing openspacemans reply, exhaust bunged up can be a problem too. How much use has the saw had?

Edited September 24 by Steven P

[AHPP]

Ed Balls

[AHPP]

Clean the filters. 

[Stubby]

As above . Start with a new plug and air filter and fuel filter .

[HillyJohn]

One other thing with these saws is to check that the choke flap in the air filter is closing for a cold start. The linkage can get bent or dislodged, making cold starts very difficult. Found this out the hard way!

[Muddy42]

As above, take off the exhaust and check if the piston is scored.  Other than that, get back to basics.  Id clean the air filter and replace the spark plug.  260s will be old saws now, rather than just cleaning the carb, Id put in a carb kit, the various rubber bits will be inflexible and brittle. Is the saw tuned or at standard carb settings?

 

Then check fuel, spark, compression and report back. Meaning does the spark plug look wet after a few pulls, can you smell fuel in the cylinder?  Can you see a spark on the plug when turning the saw over and the spark grounded against the cylinder?  Does the saw dangle on the pull cord (meaning it has compression)?

 

If it passes all these tests, then you are into pressure test territory - first the fuel line then the whole cylinder. To answer your question, a bad crank seal leak would make the saw hard to start.  But you need a P&V tester for this job and its a fairly advanced repair to tackle.

 

 

[Pete H]

Thank you all for your help, sorry for late reply, working.  I’ll do what suggested but, in all honesty I’ve already been down that route.  There is plenty of fuel to carb and air filter is the washable type which I’ve done.  I’m feeling guilty that I may appear to be ignoring you, I’m not at all.  
Stephen asked about usage, it came to me second hand, so until me I have no idea but it was mildly difficult to start, 10-12 pulls but once warm fine.

My latest attempt needed me to drip fuel onto the air filter and once going after a minute or two it seemed to scream ( weak mixture???) followed by “bogging down” eventually stopping and refusing to restart.  As much as I threatened it with the skip, it would not start until more fuel drips.

 

 

[woody paul]

Little filter in carb maybe all it is.